Preheat oven to 350F. Line a baking sheet with foil and spray with cooking spray.
Keeping the hoagie rolls whole (ignoring the slice), cut a slit along the top of each roll, being careful not to slice all the way through to the bottom or the edges. Hollow out each roll a bit by removing some of the bread from inside the slit you just cut, leaving about ½ inch of bread on the bottom. (Basically you should have a football-shaped cut-out in the top of each roll.)
Whisk together the eggs, half and half, salt, and pepper in a mixing bowl until thoroughly combined. Add 1 cup cheese and the chopped green onions and stir to combine.
In a medium skillet over medium-low heat on the stovetop, cook the eggs until almost a soft-scrambled consistency. They should still be slightly runny.
While the eggs are cooking, bake the hoagie rolls in the oven for a few minutes to crisp up. This helps them hold up better to the eggs and ensure they will not get soggy.
Remove rolls from oven and add 2 tablespoons of shredded cheese to the inside of each boat. Top with all but 2 tablespoons of crumbled bacon and the chopped mushrooms.
Add the soft-scrambled egg mixture to each breakfast boat.
Bake for 7-8 minutes. Then remove from oven and top with the remaining cheese and crumbled bacon.
Bake for another 2-3 minutes or until the cheese is melted, the bun is golden, and the filling is fully set in the center.
Allow to cool for about a few minutes before enjoying. Serve hoagies whole or cut into 2-inch segments.
Recipe adapted from: www.thekitchenwhisperer.net